Okay, let's talk about it, the closest case cited to your claim that randomly assigned buddies have been successfully sued. Note first that the suit was NOT successful.Read it again more carefully.
I. The case was used to illustrate this point (page 83):
Under this theory, "by virtue of the nature of the activity and the parties' relationship to the activity, the defendant owes no legal duty to protect the plaintiff from the particular risk of harm that caused the injury."47
II. The two were not randomly selected buddies.III. In the incident, one of them went out of air and tried to take the buddy's regulator to buddy breathe. The buddy panicked and fought off that attempt. The OOA diver drowned.
IV. Here is the analysis of the incident by the study's author:
The reasoning in Yace relied on the California Supreme Court's analogy to other sports where participants are not liable to each other for ordinary careless conduct committed during the game.55 Instead, a coparticipant only breaches his duty of care if he "intentionally injures another player or engages in conduct that is so reckless as to be totally outside the range of the ordinary activity involved in the sport."56
While there may be circumstances where a diver's negligent acts might increase the risks to his buddy and give rise to a duty of due care, the court found this was not true during an underwater emergency: "Unlike most other sports, the possibility of a life-threatening emergency in scuba diving is apparent, and indeed anticipated. Just as an emergency problem with air supply is itself an inherent risk of the sport, so also is the reaction to that emergency of one's diving buddy."57 In other words, plaintiffs' action was barred by the primary assumption of risk defense because panic constitutes an inherent risk of diving. Because Dushane panicked, or suffered "a sudden overpowering fright," his behavior could not "be characterized as careless, much less as reckless or intentional" so as to overcome the doctrine.58